Re: [PATCH v2 2/2] arm64: dts: qcom: add Xiaomi Mi 8 (dipper)

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] arm64: dts: qcom: missing TrustZone reserved memory redefinition
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commit 02ae202c9e4a6dda959a1b0bd255a44620dacac8
Author: David Heidelberg <david@ixit.cz>

arm64: dts: qcom: add Xiaomi Mi 8 (dipper)

Initial submission for one member of the prime Xiaomi Mi 8 family.
Mi 8 Pro (equuleus) and Mi 8 Explorer (ursa) are nearly identical.
Known differences are battery capacity and fingerprint sensor placement.

> diff --git a/arch/arm64/boot/dts/qcom/sdm845-xiaomi-dipper-common.dtsi b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-dipper-common.dtsi
> new file mode 100644
> index 0000000000000..eb4243e7f2c07
> --- /dev/null
> +++ b/arch/arm64/boot/dts/qcom/sdm845-xiaomi-dipper-common.dtsi
> @@ -0,0 +1,607 @@
[ ... ]
> +/delete-node/ &slpi_mem;
> +/delete-node/ &spss_mem;
> +/delete-node/ &tz_mem;
> +/delete-node/ &venus_mem;
> +/delete-node/ &wlan_msa_mem;
[ ... ]
> +	reserved-memory {
> +		/*
> +		 * It seems like reserving the old rmtfs_mem region is
> +		 * also needed to prevent random crashes
> +		 */
> +		old-rmtfs@88f00000 {
> +			reg = <0 0x88f00000 0 0x200000>;
> +			no-map;
> +		};
> +

[Severity: High]
Does this code accidentally leave TrustZone memory unreserved?

By explicitly deleting the default tz_mem node with /delete-node/ &tz_mem; at
the top of the file but failing to redefine it here in the reserved-memory
block with device-specific sizes, Linux will map the TrustZone memory space
as general-purpose System RAM.

When the buddy allocator hands out pages from this unreserved TrustZone
memory range, the system will experience random hard crashes (Synchronous
Aborts or Secure Watchdog Bites/XPU violations) when the kernel allocates
and accesses it.

The workaround of reserving old-rmtfs at 0x88f00000 to mask random crashes
appears to be a direct symptom of this missing reservation, since that memory
region falls within the unreserved TrustZone space.

> +		adsp_mem: adsp@8c500000 {
> +			reg = <0 0x8c500000 0 0x1e00000>;
> +			no-map;
> +		};

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Sashiko AI review · https://sashiko.dev/#/patchset/20260915-dipper-v2-0-cbade54919ee@ixit.cz?part=2